Convert: 600 miles per hour to km per hour

This is so hard and it’s for a test

In triangles abc and wxy, a=w and b=x which of the following must be true to prove abc=wxy by the aas theorem? a. ab=bc b. bc=xy c. ab=wx d.

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?